<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>box</title>
    <style>
        div {
            height: 200px;
            width: 300px;
            /*border: 1px solid black;*/
            /*border: 2px dashed black;*/
            border: 4px dotted black;
            /*padding: 10px;*/
            padding: 10px 20px 30px 40px;
            margin: 30px;
        }
    </style>
</head>
<body>
<div>盒子模型</div>
</body>
</html>